This invention relates to winch constructions and, more specifically, winch constructions that are employed in elevating and lowering loads.
There are a variety of winch constructions available in the marketplace presently. Most utilize a single fixed speed reduction gear box connected to a fluid motor in order to provide a given speed of drive for the winch drum or utilize a slow speed, high torque motor connected directly to the drum to provide the desired drum speed.
In many such winches, when used for elevating and lowering loads, when the cable is powered off of the winch drum (as opposed to being pulled off the drum by a load against the usual brake in a winch construction), a not infrequent occurrence is the acceleration of the drum to a speed faster than that at which it is driven due to the weight of the cable and/or a load secured therto which can cause undesirable cavitation in the fluid motor.
In order to provide more flexibility, certain manufacturers have introduced two-speed winch constructions which may be subject to the same deficiency mentioned immediately preceding. In addition, the transmissions for such two-speed winches frequently have been disposed to one or the other side of the drum with the result that the overall winch package is quite large.
Winch constructions also are used in a variety of widely varying climates and in unusually cold climates, upon startup, there may be sluggishness in the interaction of the various components. In the typical construction, sluggishness cannot be overcome without raising or lowering a load or the like and, due to the sluggishness, such a loading operation cannot be conducted properly.